Further characterization of mutants of Escherichia coli defective in membrane phospholipid synthesis are proposed. Glycerol 3-phosphate (glycerol) auxotrophs defective in the membranous glycerol 3-Phosphate acyltransferase, plsB, will be employed to investigate the effects of cessation and reinitiation of membrane phospholipid synthesis on DNA,RNA, and protein synthesis, and on cytoplasmic and outer membranes biogenesis. A study of cell growth and division by electronmicroscopy will be undertaken. The purification and physical and kinetic characterization of the wild type and feedback resistant glycerol 3-phosphate dehydrogenase will be undertaken from strains previously derived in this laboratory. A search for mutants defective in the acylglycerol 3-phosphate acyltransferase will be performed by several techniques including a radiosuicide procedure. These studies should provide novel information on the biogenesis of membrane phospholipid and its regulation in Escherichia coli. BIBLIOGRAPHIC REFERENCES: Sprague, G.F., Bell, R.M., and Cronan, J.E., Jr. (1976) "A Mutant of Escherichia coli Auxotrophic for Organic Phosphates: Evidence for two Defects in Inorganic Phosphate Transport." Mol. Gen. Genet.